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Suppressor factors generated from human mononuclear cells by means of purified myeloma proteins
Abstract:
Peripheral blood mononuclear cells (PBMC) from normal human donors were cultured in Marbrook flasks in the presence of purified IgG or IgA myeloma proteins. The culture supernatants were tested for their ability to suppress pokeweed mitogen (PWM)- or Epstein-Barr virus (EBV)-driven Ig synthesis by normal PBMC. Two supernatants from PBMC cultured with IgG and one from PBMC cultured with IgA were tested and suppressed PWM-driven Ig synthesis as measured by a reverse haemolytic plaque assay and by quantitation of the Ig secreted into the culture medium of the PWM-driven cells. This suppression was not restricted to the Ig isotype of the 'inducing' myeloma protein, but was extended to IgG, IgA, and IgM. The suppressive effect could be absorbed out with human IgG.
Insights
Normal human cells treated with myeloma proteins produced substances that suppressed immunoglobulin (Ig) synthesis. This immune suppression affected IgG, IgA, and IgM, and was absorbed by human IgG.
Area of Science:
- Immunology
- Cell Biology
- Protein Chemistry
Background:
- Immunoglobulin (Ig) synthesis is a key function of B lymphocytes.
- Myeloma proteins are monoclonal immunoglobulins produced by cancerous plasma cells.
- Understanding how external factors influence Ig synthesis is crucial for immune research.
Purpose of the Study:
- To investigate the effect of myeloma proteins on immunoglobulin synthesis by normal human peripheral blood mononuclear cells (PBMC).
- To determine if PBMC cultured with myeloma proteins can produce suppressive factors for Ig synthesis.
- To characterize the nature of this suppressive effect.
Main Methods:
- Peripheral blood mononuclear cells (PBMC) from healthy donors were cultured with purified IgG or IgA myeloma proteins.
- Culture supernatants were collected and tested for their ability to inhibit pokeweed mitogen (PWM)- or Epstein-Barr virus (EBV)-driven Ig synthesis in normal PBMC.
- Suppression was measured using a reverse hemolytic plaque assay and quantification of secreted Ig.
Main Results:
- Supernatants from PBMC cultured with IgG or IgA myeloma proteins demonstrated suppressive activity on PWM-driven Ig synthesis.
- The suppression was not limited to the isotype of the inducing myeloma protein, affecting IgG, IgA, and IgM.
- The suppressive factor could be absorbed by human IgG, suggesting its proteinaceous nature.
Conclusions:
- PBMC can generate factors that suppress Ig synthesis when exposed to myeloma proteins.
- This suppression is broad-spectrum, impacting multiple Ig isotypes.
- Human IgG plays a role in mediating or interacting with this observed immune suppression.